Process for the preparation of freeflowing detergent compositions



Un d S s Patent PROCESS FOR THE PREPARATION OF FREE- FLOWING DETERGENTCOMPOSITIONS Paul J. Schauer, Danvers, Mass., assignor to MonsantoChemical Company, St. Louis, Mo., a corporation of Delaware No Drawing.Filed June 6, 1955, Ser. No. 513,580

9 Claims. (Cl. 252-135) This invention relates to the preparation offree-flowing, spray-dried detergent compositions. More specifically theprocess of this invention relates to the direct preparation offree-flowing, spray-dried detergent compositions containing a non-ionicactive constituent and a plurality of alkaline builder components fromthe group comprising tetrasodium pyrophosphate, sodium tripolyphosphate,sodium carbonate, sodium bicarbonate, the sodium silicates, and thelike, by subjecting the spray-dried material to a fluidized aerationprocedure for a period of from about 10 to about 40 minutes,substantially immediately after discharge from the drier.

The prior art practice in the preparation of the subject.

class of detergent compositions required that the spraydried product beaged for at least 4 hours and preferably overnight prior to furthertreatment and ultimate packaging. If this were not done the productwould become badly caked in the package and blocked to the extent thatthe consumer would have difliculty in removing the proper amount ofdetergent from the package. Furthermore the unaged material causesproblems in the packaging operation and requires frequent Shllt-rdOWHSto clean and free the packaging machinery. As aforesaid, this difficultywas overcome by aging the product in small containers having a capacityof about 37 cubic feet and holding up to about 600 pounds of product. Atthe end of the aging period it was necessary to break up the cakedproduct and pass through a series of screens to classify the material.The proper-sized product was then sent to the packaging department, andthe overs were returned to the slurry preparation section of theprocess. The necessary recycle of overs is obviously inefiicient as itis wasteful of spray tion to produce a given amount of product. Inaddition the cost and maintenance of the aging vessels, the large areaneeded to store same, the excessive manual handling of the product, andthe crushing and classifying operations all add extra costs to theproduct.

In the prior art formulation of the subject detergent compositions asbulk-mixed or spray-dried products it has beenadisadvantage to use thedisclosed phosphates and carbonates, particularly in the presence ofsilicates and the active constituent, in that the hydration or agingstep required considerable time to proceed to a sufiiciently advancedstage such that the material could be safely packaged.' If thecomposition were ground, milled or packaged before the hydrationreaction was substantially complete," it was found that the materialwould cake or display a sticky condition'which'rendered the productdifficult to package with modern automatic machinery and the packagedproduct had poor shelf-life, becoming caked and blocked, thereby makingultimate use diflEicult. Whereas it is not believed that the instantfluidization process actually accelerates the aging of the detergentcomposition, it provides a means by which the product can besafelypackaged and hydration allowed to proceed" thereafter in the packagewithout danger of agglomeratiom- P ce subject spray-dried detergentcompositions by means of retaining the product in a fluidized bed for anaverage minimum time of about 10 minutes up to about 40 min-, utes ormore under the conditions hereinafter stated. As a result, the tendencyof the detergent composition to form hard lumps or agglomerates duringstorage is substantially eliminated. Thus the subject process provides asimple means to obtain a uniform, free-flowing product, which is readilyhandled in the plant packaging operation and ultimately is easilydispensed when used in industry or the home.

Fluidized beds, in general, are now well known in th chemical industrywherein they are employed to provide improved efficiency in reactionsentailing gas and solid phases. The preferred apparatus to effect thedesired fluidization of the detergent composition is very simple,essentially comprising a vertical cylindrical tower with a conicalbottom-section afixed thereto, said conical section having a perforatedplate aflixed therein at about three-quarters the distance from theinverted cone tip to the cone joint with the cylinder, which perforatedplate breaks up and distributes the air relatively evenly throughout thecross-sectional area of the tower. The product is fed into the top ofthe tower, and, after processing, is'

removed through a discharge outlet, having a suitable valve means,located just above the aforesaid perforated plate. Air is supplied tothe tower through an inlet at the tip of the cone by a multistage bloweror other suitable means. A fiared section may be affixed to the top ofthe tower section to preclude boiling out any product from the opentower in the event of slugging during the aeration process. Whereassubstantially no dust is involved in the preferred process and the towercan be safely exhausted directly into the building housing same, thetower exit gas may also be vented outside the building if desired.Formulations which may provide a minimumamount of dust in the exhaustgas stream can be cleaned up in the conventional manner by the additionof a cy-- clone separator, filter-bag dust collector, or other suitablemeans prior to exhausting the gas to the atmosphere.

The spray-dried product can be introduced into the top of the fluidizingtower by any suitable means, as by bucketelevator, pneumatic conveyor,and the like.

Whereas the aforesaid apparatus has been found to give satisfactoryresults when operated batchwise or cone, tinuously, where the productsojourn time is from about 10 minutes to about 30 minutes, otherequivalent apparatus can be employed. Thus various modifications offluidizing towers known in the prior art can be employed,

as for example, the apparatus disclosed in U.S. Patent No..-

2,690,962. Also apparatus designed to provide a plural-- ity ofsuperimposed fluidized beds, e.g. as shown in U.S. Patents No. 2,621,118and 2,697,653, can be employed in the instant process. The multi-stagefluidized-bed ar-- rangement does substantially reduce the possibleshortcircuiting of a portion of the material through the fluidized bed.However, it has been found that by operating the above-describedsingle-stage apparatus as a quiescent fluidized bed that the product hassatisfactory storage characteristics and therefore the small portion oftheproduct which may be discharged from the apparatus in less than thedesired minimum average sojourn time'doesnot adversely affect theproduct.

It was found that tower air velocities varying from 1 about 0.5 to about1 foot per second and preferably from as the fluidizing medium, air ispreferred. The tempera:

Patented June 21, 195.0,.

ture of the fluidizing gas can vary from about room temperature, i.e.C., or lower, up to about 60 C., and normally is in the neighborhood ofabout 40 C. Similarly the relative humidity of the fluidizing gas canrange from about 30 percent up to about 80 percent with substantiallyequivalent results, but the preferred condition is at about 60 percent.

The precise combination of physical and chemical effects responsible forthe observed desirable result is not known. It is acknowledged that theprior art discloses the use of air as a cooling means for hotspray-dried soap and synthetic detergent products. However theseoperations only required a contact time of the product to the air streamfor a matter of seconds. Also streams have been used .with manymaterials to remove the dust fractions.

The mechanism is clearly not one of merely cooling the product since, ascan be seen from the example, the spray-dried product enters the towerat a temperature of about 50 C., whereas the fluidizing gas can actuallyenter the tower at a higher temperature. In normal practice thefiuidizing gas temperature is about 40 C., which will eifect a drop intemperature of the product, but a gas temperature lower than the producttemperature is not critical of the subject process. Also the mechanismis not a supplemental drying process since it has been shown that arange of fiuidizing gas relative humidity of from about 30 percent toabout 80 percent can be employed without effecting any major change inthe moisture content of the product. It was found that when the relativehumidity of the gas was 30, 60, and 80 percent that the moisture contentof the product was slightly less,

about constant, and slightly increased, respectively, but

the changes were insignificant in amount.

The most logical theory relates to the possible preferential hydrationof the various components of the detergent composition. Thus the processappears to effect surface hydration of the individual particles, whilethey are freely suspended out of prolonged contact with other particles,and subsequent internal hydration can continue after the product isremoved from the fluidized zone without danger of fusing the particlestogether. By thus confining the subsequent hydration inside theindividual particles, it is possible to directly package the productwithout danger of caking or blocking in the package.

It is thus recognized that since the original spray-dried product is ofrelatively uniform particle size and the particles are suspended untilthey are stabilized against fusing together that the product would besubstantially dust free in contradistinction to aging the spray drieddetergent composition wherein the particles are in contact and becomefused together, thereby requiring a subsequent crushing operation whichfractures a portion of the original particles and causes the formationof dust. In addition to substantially eliminating dust formation, withthe savings inherent therein, the subject process also eliminates thehandling of the product in the aging step and frees a large amount ofexpensive storage space for additional production. The elimination ofthe storageaging also entails a substantial saving in labor andmaintenance. Accordingly, the unit cost of the product is reduced and amore uniform product is obtained by the subject process.

Whereas the instant process can be advantageously applied to anyspray-dried detergent formulation which contains hydrated components inthe presence of the active constituent, it is particularly adapted todetergent compositions which are based on a non-ionic active constituentand a plurality of alkaline builder components from the group comprisingtetrasodium pyrophosphate, sodium tripolyphosphate, sodium carbonate,sodium bicarbonate, the sodium silicates, and the like. The non.- ionicactive constituent is generally a condensation prodnot of the loweralkylene oxides, for example, ethylene Osi is P op e ox d y e o and m tue a '4 thereof, with a compound, or compounds, having one or more activehydrogen atoms, as for example, aliphatic mercaptans, alkyl phenols,fatty acids, alcohols, and the like. Suitable illustrative detergentcompositions are disclosed in US. Patents No. 2,522,446, 2,522,447,2,550,691, 2,572,805, 2,594,453, etc.

The detergent compositions disclosed in US. Patent No 2,550,691 areparticularly adaptable to the process of this invention. These desiredformulations have the following composition, all parts being by weight:

Parts Condensation product of tall oil with ethylene oxide in the ratioof 0.5 :2.3 per part of tall oil Tetrasodium py-rophosphate, sodiumtripolyphosphate, or mixtures thereof (anhydrous basis) 20-60 Sodiumsilicate, Na O:SiO ratio of 1:2 to 1:32

(anhy ba s) "'f-.".--.----r-#-1---:-TT--f?-T" Alkaline material selectedfrom the class consisting of sodium carbonate, sodium bicarbonate andmixtures thereof (anhydrous basis) 10-25 To the above product may beadded from 0.1 to 5 parts of oarboxymethyl cellulose.

Other more specific illustrative compositions are as follows, all partsbeing by weight:

Condensation product of one part of tall oil with 1.6 parts of ethyleneoxide 15.00 Tetrasodium pyrophosphate 4.0.00 Soda ash 20.25 Solid sodiumsilicate (G silicate) Na O:SiO =1:2 24.00. bbxv m thy el u os J PartsCondensation product of one part of tall oil with 1.8 parts of ethyleneoxide 20 Sodium tripolyphosphate .l 40 Sodium carbonate "1.; 15 Sodiumsilicate (anhydrous) Na O:SiO,-,=1:3 .2 10 t hv M 4 ar o y met y c lluos 1 '1 Condensation product of one part of tall oil with 1.6 parts ofethylene oxide 15.00 Tetrasodium pyrophosphate (anhydrous basis) 40.00Soda ash 20.15 Sodium silicate solution (water glass, 38% solids,

62% water) Na 0:Si0 =1:3.2 24.00 Carboxy methyl cellulose 0.75 Perfume(Citropene) 0.10

Condensation product of one part of tall oil with 1.5

parts of ethylene oxide ..Q 15 Sodium tripolyphosphate I. i i i 20Tetrasodium pyrophcsphate L 20 Soda ash V i v i 20 Sodium silicatesolution (38% solids) Na 0:SiO =1:3.2 24 Sodium carboxy methyl cellulosei v i 1 1 in ta t in on e a t h r ment f a. spray-dried detergentcomposition. Accordingly, the do: rese f rmul ti n are P e a d a la r seated the various ways known in' the art and spray dried,

Plieferablythe anhydrous salts of the phosphates and carbonates areemployed, since as stated in U.S. Patent No. 2,550,691, it was foundthat a better retention of the oily condensation product is obtainedwhen the hydration is eflected in the presence thereof. In the practiceof the instant invention it has also been found that the spray-drieddetergent composition should preferably contain from about 14 to about19 percent moisture for the best results, but isolated satisfactoryresults have been obtained outside these limits, which will varysomewhat for diiferent detergent formulations.

The following examples are further illustrative of this process.

Example 1 A small fluidizing tower, one foot in diameter and six feethigh having a fluidizing-gas inlet at the bottom and having means ofsupplying a controlled volume of air at controlled humidity conditions,was constructed.

Fifty-pounds of a spray-dried detergent composition, preparedinaccordance with formulation D of the above disclosure, was introducedinto the tower substantially immediately after discharge from the spraydrier. The detergent composition was fluidized for a period of about 10minutes by passing air at about 25 to 35 C. and 0.5 p.s.i.g.vpressureupwardly through the suspended solids such that the exit air velocitywas about 0.65 foot per second. Thereafter the material was passedthrough a 10-mesh screen and no lumps or agglomerates were foundtherein. Then the material was immediately packaged and subsequentlyfound to be a free-flowing product in contradistinction to the samedetergent composition which was not subjected to the fluidizing process,and wherein it was necessary to permit a static aging period of at leastfour hours, with subsequent crushing of the agglomerated product, inorder to achieve an ultimate stability of a similar nature.

Example 2 To demonstrate the effect of the relative humidity of thefluidizing gas on the moisture content of the product and the caking andblocking tendency of the packaged spray-dried detergent composition,several experiments were run wherein the relative humidity was variedfrom 30 percent to 80 percent. In this test, samples of the product wereprepared and fluidized in a similar manner to the procedure described inExample 1 and were packaged and stored for a short period of time, thenthe box tops were cut off and the material poured onto a four-meshscreen and the caked and blocked material weighed and recorded as aqualitative measure of the products, ability to remain free-flowingduring normal shelf-life. The following results were obtained:

Percent Moisture Oaking and Blocking (gms) Percent Relative ContentHumidity Min. 40 Min. 0 Min. 10 Min. 40 Min.

In all experiments it is apparent that the fluidized aeration providedimproved results. However, it appears that when the moisture content isbelow about 14 percent there is insuflicient moisture to effect rapidsurface hydration of the detergent particles and complete freedom fromcaking and blocking is not attained unless a longer aeration period isemployed. This seems to be borne out, e.g., in an additional experimentat 30 percent relative humidity wherein the original moisture contentwas 15.8 percent and the aerated product was free from caking andblocking after and 40 minutes aeration time.

. Exdmple '3 It can be demonstrated that there is no substantial changein particle size of the detergent composition dur-. ing the course ofprolonged fluidizing action, by the fact that the screen analysisremains relatively constant within the limits of experimental error:

Example 4 A larger pilot-plant fluidizing tower, about 3.5 feet indiameter and about 20 feet tall was then constructed for continuousprocess evaluation. The fluidizing gas was supplied to the tower throughan inlet at the tip of the 45 cone by a multi-stage blower capable ofdelivering 450 c.f.m. at 3 p.s.i.g. The tower was provided with aperfora'tedplate and an adjustable product outlet just above .said plateas described in the above specification.

A spray-dried detergent composition, formulationD, was continuouslypassed through an S-mesh screen (.to preclude chance introduction of anylarge agglomerates which may be formed on the spray-tower walls, etc.)and fed into the top of the fluidizing tower via a bucket elevator.tained about 3.5 feet from the top of the tower by continuously removinga portion of the. treated product through the discharge port at the samerate that the material was fed into the top of the tower. The materialwas fluidized by the introduction of air ,at about 40 C. and a relativehumidity of about-60 percent at ,a rate such that-the tower exit airvelocity was about 0.95 foot per second. The average sojourn time of thematerial was from about 15 minutes to about 20 minutes during the courseof the test. 1

I The aerated product was then packaged at a temperature of about 36 to40 C. and the aging completed within the package without caking orblocking even when the product was exposed to extremes of temperatureand humidity conditions more severe than would be required under actualmarketing conditions. Control packages of non-aerated material werefound to contain up to one-half of the contents in a caked and blockedcondition, even under normal storage conditions, and when exposed to theaccelerated storage stability test of extremes of temperature andhumidity the entire contents of the package was generally blocked andcaked.

Whereas the temperature of the spray-dried product introduced into thefluidizing tower was about 50 C. and the fluidizing gas temperature wasabout 40 C. in the above experiment, higher fluidizing gas temperaturesup to at least 60 C. have been employed with substantially the sameresults.-

I claim:

1. In the production of spray-dried detergent compositions comprising anactive nonionic o'rganic detergent constituent in the presence of ahydratable alkaline builder component, which spray-dried detergentcompositions are substantially free from caking and blocking, theimprovement which comprises introducing the hot spraydried detergentcomposition directly from the spray to'wer to a fluidizing tower andsuspending said detergent under fluidizing conditions for an averagesojourn time of from about 10 minutes to about 40 minutes.

2. In the production of spray-dried detergent compositions comprisingthe condensation product of a lower alkylene oxide with an organiccompound containing at The surface of the fluidized bed was mainaosteaz.

least one active hydrog'enatom 'formulated with a plueality o hy rata eal line builder sqmn ne s wh s ay-germ geter' em" 'ti" ""bstahaany n eam s 1' a i es intl d sm the. h t" iar'a from the spray tower to: afluidizing, K d ing said detergent under orlidit ins averagesojdurn'time 'bjf'tro'rfi about minutes to about 40 minutes.

3 The process of claim 2, wherein the spray-dried detergent compositionis selected from the following formulation," all parts b ing by weightParts Condensation product of tall oil with ethylene ox ide in theratio'of 0.5:2.3 per part or tlallQQil-lQ Phosphate materialselectedfrom the class consisting of tetrasodiumfiyrophosphate, sodiumtripolyphosphate, and. mixtures thereof (anhydrous basis) 20-60 Sodiumsilicate, Na O:SiO r at 1 .2 (anhydrous basis)' starch u, Alkalinematerial selected 'f'mni' thebla an ing of sodium carbonate;sodiumbicarb'o te and mixtures thereof (anhydrous basis);

- fa r-1s 4- Th Process o a m when ti e-hot slim-fined detergentcontains from about 14 to about -19 percent by weight of water, thefluidizing gas is air at a temperature offfrom about 20 to about 60? C.anda relative humidity of from about 30 to about 80 percent, and thefluidizing tower exit air velocity rate is from about 0.5 to about 1toot per second.

5. The process of claim 4, wherein the spraydried detergent compositionconsists of the following formulation, all parts being by weight:

' Parts Qondensation product of one part of tall oil with 1.5

parts of ethylene Sodium tripolyphosphate Tetrasodium pyrophmphafq I 20Soda ash I I 20 Sodium silicate solution (38% solids) Na QzSiO 3.2 I V24 Sodium ca'rboxy methyl cellulose 1 6. In theproduction offree-flowing, spray-dried detergent compositions. wherein the non-ionicactive constituent is'an'ethylenef oxide 'condensation product" and saidcomposition contains 'a plurality of. alkaline components from the groupconsisting of tetra'sodiuin pyropliosphafe, sodium tripolyphosphate,sodium carbonate; sodium 'bicarbonate, and a sodium silicate, theimprovement which comprises the process'of introducing the hotspray-dried detefrgent'containing from about 1410 about 19 percent by,weight of water into a tower'and sh'spendingfsaid detergent underiiuidizing conditions in azo'ne"throu'gh which a gas, inert to thedetergent, is passed upwardlyat a rate sufficient to maintain thefluidized state, a'nd'the detergent is maintained in said'fiuidizedstate for an ave a e oj urn time o om @9131 Q- Pi 91 12 29 4 i u HH HThe'process of claim 6, wherein the gas is air, at' a temperature offrom about about o0", and a relat've'humidity offrorri'aboutfit) toabout gercent'w. e e, l l p s; The process of claim 7, Whamthe suturiela l fief erences Cited in the file of this patent

1. IN THE PRODUCTION OF SPRAY-DRIED DETERGENT COMPOSITIONS COMPRISING ANACTIVE NONIONIC ORGANIC DETERGENT CONSTITUENT IN THE PRESENCE OF AHYDRATABLE ALKALINE BUILDER COMPONENT, WHICH SPRAY-DRIED DETERGENTCOMPOSITIONS ARE SUBSTANTIALLY FREE FROM CAKING A BLOCKING, THEIMPROVEMENT WHICH COMPRISES INTRODUCING THE HOT SPRAYDRIED DETERGENTCOMPOSITION DIRECTLY FROM THE SPRAY TOWER TO A FLUIDIZING TOWER ANDSUSPENDING SAID DETERGENT UNDER FLUIDIZING CONDITIONS FOR AN AVERAGESOJOURN TIME OF FROM ABOUT 10 MINUTES TO ABOUT 40 MINUTES.